Special Day Class teacher, Daryl Tran reads to Grattan Elementary student Kevin Lao, 8, during class on Tuesday April 13 2010 in San Francisco, Calif. The equipment is designed to help students with autism have and easier time playing with other students. The school has at least 28 students with autism and tries to incorporate their presence into a normal part of daily life on campus.

Photo: Mike Kepka, The Chronicle

Special Day Class teacher, Daryl Tran reads to Grattan Elementary...

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8-year-old Nathan Valerio works with the "Teach" system which is specifically designed for autistic children, at his San Bruno home.

Photo: Michael Macor, The Chronicle

8-year-old Nathan Valerio works with the "Teach" system which is...

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14-year-old Christopher Mahar, is prepared for a magnetoencephalography imaging test, which looks at brain activity, on Wednesday March 28, 2012, in San Francisco, Ca. UCSF researchers are starting a new study that involves very intensive brain imaging of kids and their parents who have a rare chromosome disruption that's connected to both autism and schizophrenia. the study is known as, The Simons Variation in Individuals Project (Simons VIP); a genetics-first approach to studying autism spectrum and related neurodevelopmental disorders.

Photo: Michael Macor, The Chronicle

14-year-old Christopher Mahar, is prepared for a...

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Jonah Fox, a 10-year-old who has autism, works on learning to swing with his therapist during a behavioral therapy session at his home in San Francisco, Calif., on Tuesday, July 19, 2011.

Photo: Laura Morton, Special To The Chronicle

Jonah Fox, a 10-year-old who has autism, works on learning to swing...

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Jonah Fox, a 10-year-old who has autism, plays basketball with his therapist during a behavioral therapy session at his home in San Francisco, Calif., on Tuesday, July 19, 2011.

Photo: Laura Morton, Special To The Chronicle

Jonah Fox, a 10-year-old who has autism, plays basketball with his...

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Joel Thesiger, 6, center, who has autism, gets a high-five while being carried by his father, Paul Thesiger, of Silver Spring, Md., at the end of the "Walk Now for Autism Speaks" event on the National Mall in Washington, on Saturday, Nov. 6, 2010. The three-mile walk funds research and raises awareness of autism.

One in 68 children in the United States has been diagnosed with autism, according to a report released Thursday from the Centers for Disease Control and Prevention, which noted that the rate has more than doubled in the past decade.

And it's likely to continue to climb, autism experts said. But the rate, while concerning, is probably not an indication that more children are developing autism - instead, doctors and other health care providers are doing a much better job finding and diagnosing kids with the disorder.

The CDC report, based on data from 2010, looked at autism diagnoses in 8-year-old children in 11 states. Rates of the disorder jumped from 1 in 88 children in 2008 and roughly 1 in 150 children in 2000.

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Media: San Francisco Chronicle

The new report underscores the need for increased resources toward treatment and prevention tools, autism experts said Thursday. That's especially true given that the cause of autism remains largely a mystery. And reflective of the increase in diagnoses is more strain on the services needed to take care of those children.

"There is an urgent need to put these findings to work for children and families," said Coleen Boyle, director of the CDC's National Center on Birth Defects and Developmental Disabilities, in a media briefing Thursday morning.

The new rates are "really tragic," said Dr. Robert Hendren, director of the autism and neurodevelopment program at UCSF Benioff Children's Hospital. "It's a huge number. If you're a parent or a grandparent or a potential parent, at this point it's really frightening. It really speaks to the need to have more funding for this."

Like previous studies of autism rates, the CDC report found large differences in diagnoses between boys and girls, along with variances based on geography and ethnicity.

One in 42 boys has autism, compared with just 1 in 189 girls, according to the CDC. White children are 30 to 50 percent more likely to be diagnosed with autism than black or Hispanic children. Among the 11 states that were part of the CDC survey, the diagnosis rate ranged from a high of 1 in 45 children in New Jersey to a low of 1 in 175 kids in Alabama.

Some of the differences in rates may be explained by the biological mechanisms of autism - boys, for example, may be more vulnerable to the disorder for reasons that scientists don't yet understand. But much of the variance more likely is due to how children are identified and diagnosed, autism experts said.

The differences in rates demonstrate the need to develop better tools for reaching out to families whose children may not have access to health care and other services that would get them diagnosed, autism experts said. Diagnosis is critical, especially in very early childhood, so that kids can receive behavioral and medical therapies that may vastly improve their symptoms as they get older, doctors said.

"We know kids respond best when they get interventions early and when the intervention is very intense," said Grace Gengoux, who specializes in child and adolescent psychiatry at Lucile Packard Children's Hospital at Stanford. "The larger numbers of children identified with autism spectrum disorders puts even greater demand and focus on those services. That has to be a priority."

Not all kids will need the same level of care. Children with no intellectual disabilities may need less intensive therapy than kids with more severe symptoms, doctors say. And, in fact, the CDC noted an increase over the past decade in the percentage of children diagnosed with autism who are of average or above average intelligence. In 2000, a third of children with autism were of at least average intelligence and in 2010, nearly half were.

Those children may partly explain the increase in rates of autism - they're further proof that doctors and other health care providers are getting better at finding kids across the full spectrum of disease, said Dr. Mark Cohen, a pediatrician at Kaiser Santa Clara who specializes in developmental delays.

"When I was first in practice, autism was extremely rare. Part of that is we were only looking at the tip of the iceberg," Cohen said. "We're getting better at picking up the more subtle cases."